A "Sancta Maria, mater Dei" (273 K.), for chorus, composed in September, 1777, and an "Alma redemptoris mater" (277 K.), for solo and chorus, of about the same date, judging by the style, are very differently conceived: they are simple in design and in treatment, quiet and mild in expression. Delicate lights and shades betray the hand of a master conscious of his power to stir the feelings and satisfy the sense of beauty of his hearers. Equal genius is displayed in the selection of simple meins, and the ease with which the right effect is given at the right moment; and every now and then a delicate harmonic inflection, or a charming little motif in the accompaniment, leaves us in no doubt as to Mozart's individuality.[52] The survey we have taken of Mozart's church music will give some idea of the industry with which he strove to master the various forms of his art, as well as of the ease and fertility of his production, and the truth of his artistic feeling. Remembering his activity in operatic music, we are amazed at the wealth of his many-sided genius; but the unceasing exercise of all his musical powers serves to explain in part that marvellous acquaintance with all the technicalities and forms of his art which not even the possession of great genius can account for in so youthful a composer. External circumstances influenced not only the conception and treatment of church music, but the means at disposal for its performance. Mozart's chief dependence in Salzburg was on the chorus, as is shown in a letter (November 4, 1777), where he says that none of his masses can be performed at Mannheim, because the chorus was bad, and the orchestra must be the first consideration. This is confirmed by the works themselves, of which the choruses are always the main substance; Mozart found his materials ready to hand in the carefully instructed church singers and chapel choir. He had himself received vocal training. Even as a boy the correct delivery and good management of his voice excited {CHURCH MUSIC.} (282) astonishment; and though he lost his voice on attaining manhood, his intercourse with trained singers gave him an accurate knowledge of the voice and its treatment. Careful as Mozart is to arrange each part easily and conveniently for performance, yet he always reckons on well-trained singers, and even exacts from the choristers, where occasion requires, not a little skill in taking intervals and in execution and intonation. Above all, he demands the intelligent delivery of a singer who knows how much depends upon it. The treatment of the solo voices as regards execution does not differ in church and operatic music. Frau Haydn and Meissner, Marie Anna Braunhofer and Jos. Spitzeder, had received good practical training, but they were not such remarkable performers as to call forth new or original creations. When the solo voices are not treated with a view to executive display they are altogether in the style of chorus parts.